The present invention relates to a circuit substrate with microprobes (hereinafter referred to as "microprobe-provided circuit substrate") as represented by a probe assembly, and a method for producing the same.
Heretofore, a microprobe-provided circuit substrate as represented by a probe assembly such as those described in Japanese Patent Unexamined Publication No. Sho-57-201039 has been produced by fixing electrically conductive metals at predetermined positions on an electrically insulating or semiconductive base manually and at the same time electrically connecting the electrically conductive metals to conductive portions to thereby arrange microprobes at predetermined positions after producing the electrically insulating or semiconductive base having the conductive portions and the electrically conductive metals constituting the microprobes as separate members.
For example, a method for producing a probe assembly used in an integrated circuit of wafer tester is as follows. Predetermined conductive portions are provided on an electrically insulating base having an opening portion at a predetermined position. Needle-shaped electrically conductive metals as microprobes formed by bending their pointed-end portions are produced separately from the base. As shown in FIGS. 26a and 26b, the electrically conductive metals 90 are fixed onto the electrically insulating base 91 with an adhesive agent 94 so that one end 90a of each of the electrically conductive metals 90 can be brought into contact with a work opening 93 side end of a corresponding conductive portion 92 provided on the electrically insulating base 91. Further, the one end 90a of the electrically conductive metal 90 is stuck to the opening 93 side end of the conductive portion 92 with solder 95, by which the electrically conductive metal and the conductive portion are electrically connected to each other. In the aforementioned method, the electrically conductive metals 90 are one by one fixed and soldered manually so that the arrangement of the bent pointed-end portions (microprobes) 90b of the electrically conductive metals 90 is adjusted to accord with the arrangement of bonding pads of an integrated circuit of wafer as a subject of the testing.
Each of the microprobes in the probe assembly is projected by a predetermined length out of a surface of the base to form a predetermined gap between the probe assembly and the tested base at the time of the testing of the base such as an integrated circuit of wafer or the like to thereby prevent the contact between the microprobe and the tested base from becoming poor in the case where foreign substances penetrate between the tested substrate and the probe assembly. In use of the probe assembly, a load of about 700 g is applied to each microprobe to prevent the contact between the microprobe and the tested substrate from becoming poor.
Therefore, high accuracy is required of the horizontal-direction and vertical-direction positions of the microprobes 90b at the time of the fixing and soldering of the electrically conductive metals 90 as shown in FIGS. 26a and 26b.
It is however difficult that the microprobes are arranged with high positional accuracy by the conventional technique in which the treatment of fixing and soldering the electrically conductive metals as precursors of microprobes onto the base is carried out by handwork. In particular, the probe assembly requires fining of the microprobes, high accuracy in positioning the microprobes and diversifying of the arrangement of the microprobes, with the advance of high integration and diversification in the integrated circuit of wafer as a subject of testing. There arises a problem in that a great skill and a large time are required for producing such a microprobe-provided circuit substrate by the conventional technique.